The grinding of cylinders and the like of considerable weight, such as for example the cylindrical rolls of a rolling mill, on a grinding machine, with maximum precision requires that the cylinder itself be held on the machine in a rotating manner, with its axis parallel to the traversing direction of the grinding tool.
In general, with the aim of having perfect coaxiality between the parts of the roll used for mounting the roll in the machine for which it is intended, such as for example a rolling mill, and the cylindrical surface to be ground, the support of the cylinder at its ends is realized by means of supporting and sliding devices, known as rests, joined to a fixed bench of the grinding machine and provided with sliding blocks, on which the mounting areas of the supports bear.
In the high-precision grinding of the surface of cylinders it is particularly important to maintain parallelism between the axis of rotation of the cylinder being worked and the direction of displacement of the tool used. In fact, an error in the parallelism leads to a conicity of the piece worked, because it sets the tool at different distances from the axis of the cylinder along its longitudinal extent and therefore such possible errors have to be compensated as soon as a conicity begins to occur during the course of machining, by a corresponding displacement of the axis of the cylinder being worked, until the optimum geometrical conditions are restored.
In the case of the known rests, fine adjustment of the position of the cylinder axis, with the aim of obtaining the parallelism desired, is achieved by manually moving the upper sliding block or possibly, in automatic machines, by motorized movement of the sliding block by means of a rocking device.
However, such structures present a number of problems attributable to the lack of rigidity of the assembly, which causes difficulty in attaining the degree of machining precision desired, and attributable to the fact that, owing to the slope of the lower sliding block with respect to the horizontal, due to the necessity of providing sufficiently stable support for the cylinder, the movement of the upper sliding block results in an upward and downward movement of the axis of the cylinder, slightly altering the geometry of the piece ground or requiring a final compensation.